ABSTRACT: Positive psychological attributes (eg, optimism) have been associated with a healthier lifestyle and superior medical outcomes in patients with type 2 diabetes; however, there has been minimal study of behavioral interventions that target positive psychological constructs in this population. Accordingly, we developed a novel, telephone-based, 12-week positive psychology intervention and assessed its feasibility and short-term impact in adults with type 2 diabetes and suboptimal health behavior adherence.This was a pilot and feasibility study in adult inpatients and outpatients at an urban academic medical center recruited between December 2013 and December 2014. Adult patients with (1) type 2 diabetes (meeting American Diabetes Association criteria, eg, glycated hemoglobin A1c [HbA1c] > 6.5% or fasting glucose > 126 mg/dL) and (2) suboptimal adherence (score < 15/18 on the Medical Outcomes Study Specific Adherence Scale items for medication, diet, and exercise) were eligible. Participants received a positive psychology manual, completed exercises (eg, writing a gratitude letter, performing acts of kindness), and reviewed these activities by phone with a study trainer over the 12-week study period. Feasibility and acceptability were assessed via exercise completion rates and postexercise ratings of ease/utility on 0-10 Likert scales. Longer-term efficacy was explored by examining changes in psychological states and health behaviors from baseline to 12 weeks using random-effects regression models and estimates of effect size.A total of 15 participants enrolled; 12 participants provided complete baseline and follow-up data and were included in the analyses. Over 90% of these participants completed at least 2 exercises, and 75% completed a majority of the exercises. Participants rated the exercises as helpful (mean = 7.8/10) and easy to complete (mean = 7.1/10), and they reported improvements in optimism, gratitude, depression, anxiety, physical function, self-care, and health behaviors (Cohen d = 0.28-1.00).A positive psychology intervention for suboptimally adherent patients with type 2 diabetes was feasible, acceptable, and associated with broad pre-post psychological and health behavior improvement in a small initial study. Further testing of this promising intervention is warranted.ClinicalTrials.gov identifier: NCT02736084.